We are studying neutrophil turnover in hematological malignancies and other causes of neutropenia. This relates to the neutrophil- mediated host defenses against bacterial infection. The four aspects of neutrophil physiology being studied can be broadly characterized as 1) marrow production 2) marrow release 3) peripheral destruction and 4) distribution (margination). The techniques that we are using include a generous marrow biopsy, measurement of marrow neutrophil reserves using the "coil test" and the etiocholanolone test, measurement of neutrophil intravascular survival utilizing the standard DFP32 test. The "coil test" is a new procedure which we are testing, consisting of reinfusion of a patient's own blood that has been exposed to cellophane in a dialysis coil. This produces a neutrophilia, the magnitude of which correlates with the marrow neutrophil reserves. Thereafter, the neutrophil count comes back to baseline at a rate closely similar to the neutrophil intravascular survival. We are also attempting to find and characterize anti-neutrophil antibodies as demonstrated by their ability to lyse neutrophils from patients with paroxysmal nocturnal hemoglobinuria. Our broad goal is to develop or improve diagnostic techniques that can help detect pathophysiological causes of neutropenia. This may improve the care of cancer patients by helping physicians choose which patients need (1) splenectomy to improve tolerance to chemotherapy, (2) reduced doses of marrow toxic drugs to avoid premature deaths from infection, and (3) steroid treatment for anti- neutrophil antibodies.